1. Related Applications
There are no applications related hereto heretofore filed in this or any foreign country.
2. Field of Invention
My invention relates generally to the removal of surface coatings by cutting and more particularly to an apparatus having a plurality of spaced, spirally oriented cutter teeth carried by a rotating cylinder that is movable over the surface to be operated upon.
3. Background and Description of Prior Art
It has become a practice in modern constructions to provide coatings for various surfaces of concrete, metal or similar materials to aid their preservation, assist in their maintenance, improve their ascetics, or otherwise improve them. Such coatings have commonly been provided on metal surfaces such as a ship's deck, bridges and like structures; on concrete surfaces such as floors, sidewalks, vehicular ramps and similar passage ways; and, increasingly, upon open exposed areas for vehicular travel such as airport runways, automotive garages, storage areas and the like. Such surface coatings commonly are relatively thick when compared to ordinary paint coatings, are both strongly adhesive and cohesive, and are of a generally semi-resilient, tough, and chemically unreactive nature, all to make them quite durable for the purposes which they normally serve, but also to render them most difficult to remove when necessary. These surface coatings heretofore known have commonly been formed of settable polymeric and resinous material such as urethane, epoxy, various other plastics, rubber-like compounds, and the like.
Such coatings, once established, do eventually become decrepit from physical wear, natural and environmental deterioration, chemical and physical change or otherwise and thereby require replacement or refurbishment. In general with such coatings as are commonly used in the present day, the old coating must be removed before a new replacement coating may be established. With many of the commonly used coating materials, a replacement coating may not be established over an existing coating, but rather the old material must be removed and a new supporting surface established such as the surface supporting the original coating. By reason of this, it has become necessary to remove the remnants of such coatings that have become decrepit in one fashion or another. My invention seeks to provide both an apparatus and method for so doing.
Such surfaces in the past generally have been removed by grinding or abrasion-type processes which have proven expensive and not too effective. Most of the coating materials that are removed are at least partially thermally plastic and since the abrading process by its nature tends to create substantial amounts of heat, it tends to some degree to plasticize the coating materials being removed to make those materials more difficult to remove, to cause them to partially adhere to the abrading medium to tend to interfere with the abrasion process, and to partially re-adhere to other removed particles and to their original supporting surface. Similarly, the abrasion process, even without the thermal plasticity of the materials involved, is a slow, time consuming one which involves substantial labor to make it economically a quite expensive process. If materials removed by abrasion are not sufficiently plastic or otherwise adapted to agglomerate, the abrasion process also tends to create undue amounts of fine particulate matter that is difficult to capture and collect and which oftentimes passes into the ambient atmosphere to cause pollution and contaminate areas outside those being operated on.
My apparatus and process seek to alleviate these problems by providing a cutting-type process for the removal of such surface coatings. Cutting tools of various sorts have heretofore been used in finer finishing of the surface of materials, such as planars or millers with wood and metal, and in the course removal of substantial portions of a material surface and its underlayment, such as in removing asphalt, tree roots and stumps, flat concrete and the like. My invention provides an intermediate-type cutter that may remove surface coatings of a medial thickness, generally in the range from 10 to 300 mills, without removing substantial amounts of the material of the supporting surface.
To do this, I provide a rotatable cylindrical cutter having a plurality of teeth projecting from the surface thereof to define an axially aligned, cylindrical cutting surface at a spaced distance outwardly from the supporting cylinder. The teeth are spirally arrayed in an axially spaced fashion so that only one, or relatively few, teeth are cutting at any particular time, but yet the cutting operation is continuous to provide a cutting action that generates a minimal amount of heat and yet prevents the chatter and vibration heretofore commonly associated with tooth type cutters, whether the cutter be operated at high or low rotary speeds. The coating removed by my cutter tends to be and remain in relatively small particles that agglomerate, otherwise are large enough so that they remain on the surface from which they were removed rather than pass into the ambient atmosphere.
The particular cylindrical form of my cutter allows it to be positioned with a high degree of precision to remove a coating from its supporting surface. The provision of separate cutting teeth also allows ready replacement of individual teeth when required and one particular tooth form also allows a releasable attachment of the cutting portion of the tooth, if desired, all to make the cutter more economical then one without replaceable teeth, since these elements sustain a substantial amount of the wear in such devices.
My cutter and its associated operative mechanism are generally configured as an auxiliary structure to be carried and positioned by some prime mover such as a small wheeled tractor. The cutting device may generally be powered by the motivating mechanism of the tractor, though in some hydraulically powered systems it may be necessary to use auxiliary devices to maintain hydraulic pressures in view of the higher fluid flows required for operation of my device. In general, small wheeled tractors provide an operating platform which is quite appropriate to provide locomotion for my cutter structure. In general, the locomoting mechanism should allow adjustable positioning of my invention to regulate depth of cut and it is most convenient if such mechanism also allows angular positioning about an axis elongate to the tractor to allow my cutter to accommodate sloping surfaces such as on ramps and the like. Prior art devices in general have not provided this type of mounting, as indeed such mounting generally has not been required for the operation of such devices.
Commonly, most coated surfaces that will require removal are horizontal or substantially so, but sometimes coatings on vertical surfaces, especially those defining the periphery of a horizontal surface, require removal. In this later situation, it is convenient to provide a primary cutter oriented about a horizontal axis and a secondary cutter oriented about a vertical axis to remove coatings from such vertical surfaces. The secondary cutter may conveniently be mounted by a positioning structure at one or both ends of a primary horizontal cutter so that the vertical cutter may extend beyond the lateral periphery of a propelling tractor to allow free and unencumbered use.
My invention further provides a housing for my cutter structures which enclose a substantial amount of the cutter periphery, with only a small sector where cutting actually occurs being open. This provides not only a safety shield to prevent access to the cutter during operation and prevent debris from being thrown randomly by it, but also provides a means to mount and contain a water spray system. Such water spray system sprays water upon the cutter within the housing and the area of its operation upon an adjacent surface. This water aids in containment of debris and also provides coolant to the tooth structure of the cutter and prevents thermal plasticity in the coating being cut. Devices of the prior art in general have not provided water spray upon the surface removing element, either because the water was unnecessary, there was no means of getting the water to the actual surface removing process, or there was no means of containing a water spray.
My invention resides not in any one of these structural features or methods, per se, but rather in the unique synergistic combination of all of them to provide the functions necessarily flowing therefrom.